%0 Journal Article
%T AlPO4-54-AlPO4-8 Structural Phase Transition and Amorphization under High Pressure
%+ Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM)
%+ Synchrotron SOLEIL (SSOLEIL)
%+ Laboratoire Charles Coulomb (L2C)
%A Alabarse, Frederico
%A Brubach, Jean-Blaise
%A Roy, Pascale
%A Haidoux, Abel
%A Levelut, Claire
%A Bantignies, Jean-Louis
%A Cambon, Olivier
%A Haines, Julien
%< avec comité de lecture
%Z L2C:15-154
%@ 1932-7447
%J Journal of Physical Chemistry C
%I American Chemical Society
%V 119
%N 14
%P 7771-7779
%8 2015-04-09
%D 2015
%R 10.1021/acs.jpcc.5b00318
%Z Chemical Sciences/Material chemistryJournal articles
%X Microporous AlPO4-54, which exhibits the largest pores among zeolites and aluminophosphates with a diameter of 12.7 Å, was investigated at high pressure by X-ray powder diffraction (XRD), mid- and far-infrared (IR) spectroscopy in diamond anvil cells. The material undergoes a phase transition beginning around 0.8 GPa. The amount of AlPO4-8 gradually increases with pressure and the phase transition is complete between 2 and 3 GPa. The closure of the (P—O—Al) angle destabilizes the structure of AlPO4-54, which drives the transition to AlPO4-8. The pressure-induced phase transformation of AlPO4-54 to AlPO4-8 is associated with a symmetry reduction from hexagonal to orthorhombic and with a change in the unidirectional ring channel parallel to the c-axes from 18 to 14 AlO4 and PO4 tetrahedra. An abrupt decrease along the b direction is linked to the formation of 4 new rings of 6 tetrahedra with significant structural reorganization. The transition is followed by irreversible amorphization beginning around 3.5 GPa due to the collapse of the pores. The amorphization of AlPO4-8 was detected from the disappearance of the XRD lines, abrupt shifts, and strong broadening of the mid-IR modes, and by changes in the pressure dependence of the mid- and far-IR modes, indicating a lower compressibility for the more dense amorphous form. Far-IR spectra indicate that the new amorphous form retains the local structure of AlPO4-8.
%G English
%L hal-01202111
%U https://hal.science/hal-01202111
%~ CNRS
%~ ENSC-MONTPELLIER
%~ ICG
%~ L2C
%~ INC-CNRS
%~ SYNCHROTRON-SOLEIL
%~ MIPS
%~ CHIMIE
%~ UNIV-MONTPELLIER
%~ GS-PHYSIQUE
%~ INSTITUT-SCIENCES-LUMIERE
%~ UM-2015-2021